Electronic device

ABSTRACT

In a conventional electronic device and a method of manufacturing the same, reduction in cost of the electronic device is hindered because resin used in an interconnect layer on the solder ball side is limited. The electronic device includes an interconnect layer (a first interconnect layer) and an interconnect layer (a second interconnect layer). The second interconnect layer is formed on the undersurface of the first interconnect layer. The second interconnect layer is larger in area seen from the top than the first interconnect layer and is extended to the outside from the first interconnect layer.

This application is based on Japanese patent application NO.2006-271154, the content of which is incorporated hereinto by reference.

BACKGROUND

1. Technical Field

The present invention relates to an electronic device and a method ofmanufacturing the same.

2. Related Art

As a known method of manufacturing an electronic device, for example,there is provided one which is disclosed in Japanese Laid-open patentpublication No. 2003-309215. In a manufacturing method described in thesame document, a multilayer interconnect layer is formed by laminating aplurality of interconnect layers on a supporting substrate, and then,the supporting substrate is removed. Then, a solder ball is formed as anexternal electrode terminal on one surface of the multilayerinterconnect layer which is exposed by the removal of the supportingsubstrate. Furthermore, electronic components are mounted in a flip chipconfiguration on the other surface of the multilayer interconnect layer.This can obtain an electronic device on which electronic components areplaced on the multilayer interconnect layer.

In addition, as conventional art documents related to the presentinvention, there may be included Japanese Laid-open patent publicationNos. 57-7147, 9-321408, 11-126978, 2001-53413 in addition to JapaneseLaid-open patent publication No. 2003-309215.

By the way, in the above electronic device, in order to performmicroscopic connection between the interconnect layer and the electroniccomponent, resin suitable for micromachining is required to be used inan interconnect layer on the electronic component side in theinterconnect layers which constitute the multilayer interconnect layer.On the other hand, there are many cases where the resin suitable formicromachining is not required to be used in an interconnect layer onthe solder ball side. In this case, it is preferable to use resin withrelatively low cost in the interconnect layer on the solder ball side toreduce costs of the electronic device.

However, in the manufacturing method disclosed in Japanese Laid-openpatent publication No. 2003-309215, as described above, the multilayerinterconnect layer is formed by laminating a plurality of interconnectlayers in order on the supporting substrate. Therefore, the interconnectlayer on the solder ball side is formed prior to forming theinterconnect layer on the electronic component side. As a result, thereis a restriction in that resin which is lower in decompositiontemperature than the resin which constitutes the interconnect layer onthe electronic component side cannot be used as the resin whichconstitutes the interconnect layer on the solder ball side. The resinfor use in the interconnect layer on the solder ball side is limited forsuch a restriction, and accordingly, reduction in cost of the electronicdevice is hindered.

SUMMARY

In one embodiment, there is provided a method of manufacturing anelectronic device, including: forming a first interconnect layer on asupporting substrate; removing said supporting substrate;

and forming a second interconnect layer, said second interconnect layerextending to further outside than said first interconnect layer beingformed on a surface of said first interconnect layer where saidsupporting substrate is removed.

There is provided a method of manufacturing an electronic device,including: wherein in the step of said forming second interconnectlayer, a resin which is lower is in decomposition temperature than aresin which constitutes said first interconnect layer is used as a resinwhich constitutes said second interconnect layer. Therefore, resinsuitable for micromachining can be used in the first interconnect layer;on the other hand, resin with relatively low cost can be used in thesecond interconnect layer.

Furthermore, in one embodiment, there is provided an electronic deviceincluding: a first interconnect layer; and a second interconnect layerwhich is provided on the first interconnect layer and extended tofurther outside than the first interconnect layer.

In this electronic device, as a resin which constitutes the secondinterconnect layer, resin which is lower in decomposition temperaturethan resin which constitutes the first interconnect layer can be used.Therefore, resin suitable for micromachining can be used in the firstinterconnect layer; on the other hand, resin with relatively low costcan be used in the second interconnect layer.

According to the present invention, there can be implemented anelectronic device and a method of manufacturing the same, both of whichare capable of obtaining microscopic connection between an interconnectlayer and an electronic component with low cost.

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects, advantages and features of the presentinvention will be more apparent from the following description ofcertain preferred embodiments taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a cross-sectional view showing a first embodiment of anelectronic device according to the present invention;

FIG. 2 is a cross-sectional view for explaining an example of astructure in the vicinity of an interface between a first interconnectlayer and a second interconnect layer;

FIGS. 3A to 3E are process views showing a general outline of the firstembodiment of a method of manufacturing an electronic device accordingto the present invention;

FIGS. 4A and 4B are process views showing the first embodiment of themethod of manufacturing the electronic device according to the presentinvention;

FIGS. 5A and 5B are process views showing the first embodiment of themethod of manufacturing the electronic device according to the presentinvention;

FIGS. 6A and 6B are process views showing the first embodiment of themethod of manufacturing the electronic device according to the presentinvention;

FIG. 7 is a process view showing the first embodiment of the method ofmanufacturing the electronic device according to the present invention;

FIG. 8 is a cross-sectional view showing a second embodiment of anelectronic device according to the present invention;

FIGS. 9A and 9B are process views showing the second embodiment of amethod of manufacturing an electronic device according to the presentinvention;

FIGS. 10A to 10C are process views showing the second embodiment of themethod of manufacturing the electronic device according to the presentinvention;

FIGS. 11A and 11B are process views showing the second embodiment of themethod of manufacturing the electronic device according to the presentinvention;

FIGS. 12A and 12B are process views showing the second embodiment of themethod of manufacturing the electronic device according to the presentinvention;

FIG. 13 is a cross-sectional view showing a third embodiment of anelectronic device according to the present invention;

FIGS. 14A and 14B are process views showing the third embodiment of amethod of manufacturing an electronic device according to the presentinvention;

FIG. 15 is a plan view for explaining a modified example of anembodiment; and

FIGS. 16A to 16C are plan views for explaining modified examples ofembodiments.

DETAILED DESCRIPTION

The invention will be now described herein with reference toillustrative embodiments. Those skilled in the art will recognize thatmany alternative embodiments can be accomplished using the teachings ofthe present invention and that the invention is not limited to theembodiments illustrated for explanatory purposed.

Preferred embodiments of electronic devices and methods of manufacturingthe same according to the present invention will be described in detailbelow with reference to the drawings. In addition, the same referencenumerals are given to those identical to constitutional elements in thedescription of the drawings and their detail description will not berepeated.

First Embodiment

FIG. 1 is a cross-sectional view showing a first embodiment of anelectronic device according to the present invention. An electronicdevice 1 includes an interconnect layer 10 (a first interconnect layer)and an interconnect layer 20 (a second interconnect layer).

The interconnect layer 10 has a via plug 12 (a first conductive plug),an insulation resin 14, and conductor interconnect 16. The via plug 12is formed in the insulation resin 14. As can be seen from the drawing,the via plug 12 is of a tapered shape which becomes smaller in diameteras approaching to the interconnect layer 20. Therefore, an end surfacearea on the interconnect layer 20 side of the via plug 12 is smallerthan an end surface area opposite thereto, that is, an end surface areaon the IC chip 32 and 36 sides (to be described later).

A conductor of the via plug 12 is Cu, Ni, Au, or Ag, for example. Theinsulation resin 14 is, for example, polyimide resin, polybenzoxazole(referred to as PBO) resin, benzocyclobutene (referred to as BCB) resin,cardo resin (cardo-type polymer), or epoxy resin. The polyimide resinmay be photosensitive polyimide resin, or non-photosensitive polyimideresin. The conductor interconnect 16 connected to the via plug 12 isformed on the insulation resin 14.

The IC chips 32 and 36 (electronic components) are placed on an uppersurface (a first surface) of the interconnect layer 10. Each of the ICchips 32 and 36 is connected in a flip chip configuration to theconductor interconnect 16 via bumps 33 and 37. An underfill resin 34 isfilled in a gap between the IC chip 32 and the interconnect layer 10. Inthe same way, an underfill resin 38 is filled in a gap between the ICchip 36 and the interconnect layer 10. The IC chip 36 is provided inplural number, and those chips are laminated with each other. The ICchip 32 and the IC chip 36 are a CPU and a laminated memory,respectively. The laminated memory is one in which an IC chip (memory)is three-dimensionally laminated and electrically connected between thechips (memories).

In addition, the IC chips 32 and 36 are covered with a sealing resin 52formed on the interconnect layer 10. In more detail, side surfaces ofthe IC chip 32, side surfaces and an upper surface of the IC chip 36 arecovered with the sealing resin 52.

The interconnect layer 20 is formed on an undersurface (a secondsurface) of the interconnect layer 10. The interconnect layer 20 islarger in area seen from the top than the interconnect layer 10 and isextended to further outside than the interconnect layer 10. That is, theinterconnect layer 20 is protruded from the interconnect layer 10.

The interconnect layer 20 has a via plug 22 (a second conductive plug)and an insulation resin 24. The via plug 22 is formed in the insulationresin 24. The via plug 22 is connected to the above mentioned via plug12. As can be seen from the drawing, the via plug 22 is of a taperedshape which becomes smaller in diameter as approaching to theinterconnect layer 10. Therefore, an end surface area on theinterconnect layer 10 side of the via plug 22 is smaller than an endsurface area opposite thereto, that is, an end surface area on solderball 60 sides. A conductor of the via plug 22 is, for example, Cu, Ni,Au, or Ag, as in the via plug 12. Furthermore, the insulation resin 24is, for example, epoxy resin or the like. An interconnect body composedof the above mentioned interconnect layer 10 and interconnect layer 20functions as an interposer in the electronic device 1.

Decomposition temperature of the insulation resin 14 which constitutesthe interconnect layer 10 is higher than that of the insulation resin 24which constitutes the interconnect layer 20. In case of using PBO as theinsulation resin 14, its decomposition temperature is 540° C., forexample. Furthermore, in case of using epoxy resin as the insulationresin 24, its decomposition temperature is 310° C., for example. In thiscase, the decomposition temperature is a temperature at the time whenthe resin weight is reduced by 5 wt % when measured with a thermobalanceat a rate of temperature increase of 10° C./min. In addition, even whenthe same type of resin (for example, epoxy resin) is used as theinsulation resins 14 and 24, the former is higher in decompositiontemperature than the latter.

An IC chip 42 and a passive component 44 are placed on a further outsideportion than the interconnect layer 10 in the interconnect layer 20, assecond electronic components. The passive component 44 is, for example,a capacitor such as a decoupling capacitor. The IC chip 42 is coveredwith a sealing resin 54. The passive component 44 is covered with aresin 56 provided on an outside portion of the interconnect layer 20.The resin 56 may be the same resin as the sealing resin 54, or may bedifferent resin.

Furthermore, the interconnect layer 20 is of a multilayer interconnectstructure, and has conductor interconnect 26 provided in plural layersand a via plug 28 which connects the conductor interconnects 26 ofdifferent layers. The solder ball 60 is connected to the conductorinterconnect 26 at the lowermost layer. A part of the solder ball 60 isburied in a solder resist 62. The solder ball 60 functions as anexternal connection terminal of the electronic device 1.

Referring to FIG. 2, an example of a structure in the vicinity of aninterface between the interconnect layer 10 and the interconnect layer20 will be described. In this example, an adhesion metal film 72 isformed so as to cover the via plug 22. The adhesion metal film 72 comesin contact with the via plug 12 on the via plug 22. Further, an adhesionmetal film 74 is formed also on a surface which comes in contact withthe via plug 12 of the conductor interconnect 16.

It is preferable that the adhesion metal films 72 and 74 are a filmincluding Ti (for example, Ti, TiN, TiW, or the like), or a Cr film.

Referring to FIGS. 3A to 7, as the first embodiment of a method ofmanufacturing an electronic device according to the present invention, amethod of manufacturing an electronic device 1 will be described. Inadvance of detail description, an outline of the present manufacturingmethod will be described using FIGS. 3A to 3E. First, as shown in FIG.3A, an interconnect layer 10 is formed on a supporting substrate 90 (afirst interconnect layer formation process). As the supporting substrate90, a silicon substrate, a ceramic substrate, a glass substrate, a metalsubstrate, or the like can be used.

Next, as shown in FIG. 3B, IC chips 32 and 36 are placed on theinterconnect layer 10 (an electronic component placing process).Further, as shown in FIG. 3C, a sealing resin 52 is formed on theinterconnect layer 10 so as to cover the IC chips 32 and 36 (a sealingresin formation process). Subsequently, as shown in FIG. 3D, thesupporting substrate 90 is removed (a supporting substrate removalprocess). After that, as shown in FIG. 3E, an interconnect layer 20 isformed on an undersurface of the interconnect layer 10 (a secondinterconnect layer formation process). Last, although not shown in thedrawing, the electronic device 1 shown in FIG. 1 is obtained by forminga solder ball 60.

Subsequently, the present manufacturing method will be described usingFIGS. 4A to 7. First, an insulation resin 14 is formed on the supportingsubstrate 90, and a via plug 12 is formed therein. After that, aconductor interconnect 16 is formed on the insulation resin 14 (FIG.4A). Next, the IC chips 32 and 36 are mounted in a flip chipconfiguration on the conductor interconnect 16 (FIG. 4B). Subsequently,the sealing resin 52 is formed on the interconnect layer 10 so as tocover the IC chips 32 and 36. Formation of the sealing resin 52 can beperformed by, for example, a molding method, a printing method or apotting method (FIG. 5A). After that, the undersurface of theinterconnect layer 10 is exposed by removing the supporting substrate 90(FIG. 5B).

Next, an insulation resin 24 is formed on the undersurface of theinterconnect layer 10 so as to extend to further outside than theinterconnect layer 10. At this time, for example, an insulation film canbe used as the insulation resin 24. Subsequently, an IC chip 42 and apassive component 44 are mounted on a further outside portion than theinterconnect layer 10 of the insulation resin 24. After that, a sealingresin 54 is formed so as to cover the IC chip 42 (FIG. 6A). Next, aresin 56 is formed so as to bury a gap formed on the outside portion ofthe insulation resin 24. This covers the passive component 44 with theresin 56 (FIG. 6B).

Next, a via plug 22 is formed in the insulation resin 24 so as to beconnected to the via plug 12. After that, a build-up interconnect layeris formed on the insulation resin 24. For example, a conductorinterconnect 26 by a semi-additive method and the via plug 28 by a laserprocess may be alternatively formed in insulation resin layers such asepoxy resin. This forms the interconnect layer 20 (FIG. 7). After that,the electronic device 1 shown in FIG. 1 can be obtained by forming asolder resist 62 and the solder ball 60. In addition, formation of theinterconnect layer 20 may be performed by adhering a preliminarilyformed multilayer interconnect layer on the undersurface of theinterconnect layer 10 as the interconnect layer 20.

As is apparent from the above description, build-up directions of theinterconnect layers 10 and 20 are upward and downward directions in thedrawing, respectively. Accordingly, as described above, an end surfaceon the IC chips 32 and 36 sides of the via plug 12 is larger in areathan an end surface on the interconnect layer 20 side, and an endsurface on the solder ball 60 side of the via plug 22 is larger in areathan an end surface on the interconnect layer 10 side.

Effects of the present embodiment will be described. In the abovemanufacturing method, the interconnect layer 10 on which the IC chips 32and 36 are placed is formed on the supporting substrate 90, whereas, theinterconnect layer 20 is formed after removing the supporting substrate90. This can escape from restriction in that, as the insulation resin24, resin which is lower in decomposition temperature than theinsulation resin 14 cannot be used. Therefore, resin suitable formicromachining can be used as the insulation resin 14; on the otherhand, resin with relatively low cost can be used as the insulation resin24. This can implement a method of manufacturing the electronic device1, which is capable of obtaining microscopic connection between theinterconnect layer 10 and the IC chip 32 and 36 with low cost.

Further, the interconnect layer 20 extends to further outside than theinterconnect layer 10. This can sufficiently increase an area of asurface (that is, the undersurface of the interconnect layer 20) onwhich the solder ball 60 is provided, while suppressing the area of theinterconnect layer 10 small. Therefore, the electronic device 1 can beeasily mounted on other electronic devices, mother boards, and the likewithout increasing cost. On the other hand, in the case where theinterconnect layer 10 and the interconnect layer 20 are equal in areawith each other, if the area of the interconnect layer 20 is increasedto enhance mountability, accordingly the area of the interconnect layer10 has to be increased. Then, since relatively expensive resin suitablefor micromachining is used for the interconnect layer 10, manufacturingcost of the electronic device 1 increases. On the other hand, if thearea of the interconnect layer 10 is decreased to reduce costs, the areaof the interconnect layer 20 decreases and mountability is impaired.According to the present embodiment, such dilemma can be solved and abalance between low cost and mountability can be achieved.

Interconnect patterns of the conductor interconnect 16 are formed on thesupporting substrate 90 which is high rigidity, and therefore,microscopic conductor interconnect 16 can be obtained. In addition,since the interconnect layer 10 and the IC chips 32 and 36 are bonded onthe supporting substrate 90, the interconnect layer 10 and the IC chips32 and 36 are connected by a bump connection at a microscopic pitch.This leads to reduction in number of the interconnect layers andreduction in size of the IC chips 32 and 36.

Further, since the interconnect layer 20 is formed after removing thesupporting substrate 90, the insulation resin 24 which constitutes theinterconnect layer 20 can be formed thicker than the insulation resin14. This enhances stress reduction function of the insulation resin 24and leads to an improvement in reliability of the electronic device 1.

In the second interconnect layer formation process, the resin which islower in decomposition temperature than the insulation resin 14 whichconstitutes the interconnect layer 10 formed in the first interconnectlayer formation process is used as the insulation resin 24 whichconstitutes the interconnect layer 20. This can preferably form theinterconnect layer 20 on the interconnect layer 10.

In the electronic device 1, the resin which is lower in decompositiontemperature than the insulation resin 14 which constitutes theinterconnect layer 10 can be used as the insulation resin 24 whichconstitutes the interconnect layer 20. Therefore, the resin suitable formicromachining can be used as the insulation resin 14; on the otherhand, the resin with relatively low cost can be used as the insulationresin 24. This can implement the electronic device 1, which is capableof obtaining microscopic connection between the interconnect layer 10and the IC chip 32 and 36 with low cost.

Further, in the electronic device 1, the interconnect layer 10 and theinterconnect layer 20 are directly connected, and therefore, a corelayer is not provided therebetween. Since it is difficult to achieveminiaturization of the via plug formed in the core layer as comparedwith a via plug generally formed in a usual interconnect layer, there isa problem in that the entire miniaturization of the electronic device ishindered. In this regard, in the electronic device 1, the core layer isnot provided, and therefore, such problem is not generated.

The sealing resin 52 is provided so as to cover the IC chips 32 and 36.With this configuration, the shape of the interconnect body can bemaintained even after the supporting substrate 90 is removed. Therefore,the solder ball 60 with high coplanarity can be obtained. Particularly,in the present embodiment, the resin 56 is formed even on the furtheroutside portion than the interconnect layer 10 of the interconnect layer20, thereby further enhancing such effect.

In the case where the silicon substrate is used as the supportingsubstrate 90, influence of thermal expansion can be suppressed small ascompared with the case where an insulation substrate is used. With thisconfiguration, miniaturization of connection between the interconnectlayer 10 and the IC chips 32 and 36 can be further performed.

In the case where polyimide resin, PBO resin, BCB resin, or cardo resinis used as the insulation resin 14, the insulation resin 14 suitable formicromachining is achieved. In addition, in the case where epoxy resinis used as the insulation resin 24, the insulation resin 24 can beobtained at low cost.

An adhesion metal film 72 is provided so as to cover the via plug 22(see FIG. 2). This can obtain strong conjunction between the via plug 22and the insulation resin 24. In addition, an adhesion metal film 74 isprovided on a surface which comes in contact with the via plug 12 of theconductor interconnect 16 (see FIG. 2). This can obtain strongconjunction between the conductor interconnect 16 and the insulationresin 14. This contributes to an improvement in reliability of theelectronic device 1. In the case where the adhesion metal films 72 and74 include Ti, or the adhesion metal films are made of Cr; especiallyhigh adhesiveness to the resin can be obtained.

The IC chip 42 and the passive component 44 can be placed on the furtheroutside portion than the interconnect layer 10 in the interconnect layer20. This can further increase in function and performance of theelectronic device 1.

Second Embodiment

FIG. 8 is a cross-sectional view showing a second embodiment of anelectronic device according to the present invention. The electronicdevice 2 includes an interconnect layer 10 (a first interconnect layer)and interconnect layer 80 (a second interconnect layer). Configurationof the interconnect layer 10 is the same as that described in FIG. 1.

The interconnect layer 80 is formed on an undersurface of theinterconnect layer 10 and extended to further outside than theinterconnect layer 10. The interconnect layer 80 has a solder resist 84and conductor interconnect 86 formed therein. Resin which is lower indecomposition temperature than an insulation resin 14 is used as thesolder resist 84. A via plug 82 (a second conductive plug) is formed inthe interconnect layer 80. The via plug 82 corresponds to a portionburied in a part of a solder ball 60, specifically in the solder resist84 in the solder ball 60. As can be seen from the drawing, the via plug82 is of a tapered shape which becomes smaller in diameter asapproaching to the interconnect layer 10. Therefore, an end surface areaon the interconnect layer 10 side of the via plug 82 is smaller than anend surface area opposite thereto.

Further, an IC chip 92 is mounted in a flip chip configuration on anundersurface of the interconnect layer 10. That is, the IC chip 92 isconnected to the undersurface via a bump 93, and underfill resin 94 isfilled in a gap between the interconnect layer 10 and the IC chip 92.

A resin 56 is formed on a further outside portion than the interconnectlayer 10 in the interconnect layer 80. In the present embodiment, theresin 56 covers side surfaces and an upper surface of a sealing resin52.

Referring to FIGS. 9A to 12B, as the second embodiment of a method ofmanufacturing an electronic device according to the present invention, amethod of manufacturing an electronic device 2 will be described. First,an insulation resin 14, a via plug 12, and conductor interconnect 16 areformed on a supporting substrate 90 (FIG. 9A). Subsequently, IC chips 32and 36 are mounted in a flip chip configuration on the conductorinterconnect 16 (FIG. 9B).

Next, a sealing resin 52 is formed on an interconnect layer 10 so as tocover the IC chips 32 and 36 (FIG. 10A). After that, an undersurface ofthe interconnect layer 10 is exposed by removing the supportingsubstrate 90 (FIG. 10B). Subsequently, a supporting seat 91 is formed onthe undersurface of the interconnect layer 10 so to extend to furtheroutside than the interconnect layer 10 (FIG. 10C).

Next, a resin 56 is formed on a further outside portion than theinterconnect layer 10 of the supporting seat 91 by covering the sealingresin 52 (FIG. 11A). After that, the supporting seat 91 is separated(FIG. 11B). Next, conductor interconnect 86 is formed on theundersurface of the interconnect layer 10, and then, a solder resist 84is formed so as to cover the conductor interconnect 86. Further,patterning of the solder resist 84 is performed, and a portion where asolder ball 60 is formed and a portion where an IC chip 92 is mountedare opened (FIG. 12A). This forms an interconnect layer 80.Subsequently, the IC chip 92 is mounted in a flip chip configuration onthe undersurface of the interconnect layer 10 (FIG. 12B). After that,the electronic device 2 shown in FIG. 8 can be obtained by forming thesolder ball 60.

The present embodiment can exhibit the following effect in addition tothe effects of the above described first embodiment. The solder resist84 is used as the resin which constitutes the interconnect layer 80, andtherefore, the electronic device 2 can be further reduced in cost.Further, the electronic component (IC chip 92) is mounted not only on anupper surface of the interconnect layer 10 but also on the under surfacethereof, whereby the electronic device 2 can be further increased infunction and performance.

Third Embodiment

FIG. 13 is a cross-sectional view showing a third embodiment of anelectronic device according to the present invention. The electronicdevice 3 includes an interconnect layer 10 and an interconnect layer 80.The electronic device 3 is different from the electronic device 2 shownin FIG. 8 in that the interconnect layer 80 has a multilayerinterconnect structure. In the present embodiment, the interconnectlayer 80 includes an insulation resin 84 a provided on an undersurfaceof the interconnect layer 10 and a solder resist 84 b provided thereon.

In the interconnect layer 80 of the present embodiment, conductorinterconnect 86 provided in plural layers and a via plug 83 (a secondconductive plug) connected to the conductor interconnect 86 are formed.As can be seen from the drawing, the via plug 83 is of a tapered shapewhich becomes smaller in diameter as approaching to the interconnectlayer 10. Therefore, an end surface area on the interconnect layer 10side of the via plug 83 is smaller than an end surface area oppositethereto. In addition, the bump 93 is directly connected to the via plug12 in the electronic device 2, whereas, a bump 93 is connected to a viaplug 12 via the conductor interconnect 86 (and the via plug 83) in theelectronic device 3. Other configuration of the electronic device 3 isthe same as the electronic device 2.

Referring to FIGS. 14A and 14B, as the third embodiment of a method ofmanufacturing an electronic device according to the present invention, amethod of manufacturing an electronic device 3 will be described. First,a structure shown in FIG. 11B is prepared as described in FIGS. 9A to11B.

Next, a first layer conductor interconnect 86 is formed on anundersurface of the interconnect layer 10 so as to be connected to a viaplug 12. After that, an insulation resin 84 a is formed so as to coverthe first layer conductor interconnect 86. Further, a via plug 83 isformed so as to be connected to the conductor interconnect 86 in theinsulation resin 84 a. Subsequently, a second layer conductorinterconnect 86 is formed on the insulation resin 84 a so as to beconnected to the via plug 83. After that, a solder resist 84 b is formedso as to cover the second layer conductor interconnect 86.

Next, patterning of the solder resist 84 b is performed, and a portionwhere a solder ball 60 is formed and a portion where an IC chip 92 ismounted are opened (FIG. 14A). This forms an interconnect layer 80.Subsequently, the IC chip 92 is mounted in a flip chip configuration onthe insulation resin 84 a (FIG. 14B). After that, the electronic device3 shown in FIG. 13 can be obtained by forming the solder ball 60. Thesame effects as the second embodiment can be exhibited even in thepresent embodiment.

The electronic devices and the methods of manufacturing the sameaccording to the present invention are not limited to the aboveembodiments, but, various modifications can be made. For example, in theabove embodiments, the IC chip is exemplified as the electroniccomponent placed on the upper surface or the undersurface of theinterconnect layer 10; however, the electronic component may be apassive component such as a capacitor. In addition, it is not necessaryto provide the electronic component in the electronic device.

In the above embodiments, the example in which the solder ball isprovided in the electronic device; however, it is not necessary toprovide the solder ball. In the case where the solder ball is notprovided, a land portion of the conductor interconnect corresponds to anexternal electrode terminal. When the electronic device 1 shown in FIG.1 is taken for an example, a portion where the solder ball 60 isconnected in the conductor interconnect 26 is a land portion.

In addition, the second interconnect layer may be protruded from thewhole periphery of the first interconnect layer, or may be protrudedfrom only one part thereof. The former example is shown in FIG. 15, andthe latter example is shown in FIGS. 16A to 16C. In these plan views,outer peripheries of the first and the second interconnect layers areshown by lines L1 and L2, respectively; and a portion where bothinterconnect layers are overlapped are shaded. In FIG. 15, the secondinterconnect layer is protruded from all four sides of the firstinterconnect layer. On the other hand, in FIGS. 16A, FIGS. 16B, and 16C,the second interconnect layers are protruded from three sides, twosides, and one side of the first interconnect layers, respectively.

It is apparent that the present invention is not limited to the aboveembodiment, and may be modified and changed without departing from thescope and spirit of the invention.

What is claimed is:
 1. A electronic device comprising: an interconnectlayer having a first main surface and a second main surface opposite thefirst main surface; a first semiconductor chip arranged above the firstmain surface and having a first obverse surface, a CPU circuit formed onthe first obverse surface; a plurality of second semiconductor chipsarranged above the first main surface and laminated to each other; athird semiconductor chip having a second obverse surface, an electrodeformed on the second obverse surface; and a plurality of externalelectrodes formed on the second main surface of the interconnect layer,wherein each of the second semiconductor chips has an upper surface anda back surface opposite the upper surface, a memory circuit on the uppersurface, and a through via plug formed from the upper surface to theback surface, wherein the second semiconductor chips are electricallyconnected each other through the through via plugs, wherein a firstconductive plug connects the electrode with the through via plug,wherein the third semiconductor chip is arranged in verticalregistration right under the second semiconductor chips and the thirdsemiconductor chip is located within an outer perimeter of the secondsemiconductor chips in a plan view, and wherein, in a cross sectionview, the through via plug, the first conductive plug and the electrodeare arranged vertically in a straight line in a middle part of thesecond semiconductor chips and the third semiconductor chip.
 2. Theelectronic device according to claim 1, wherein, the first conductiveplug has a first end surface area and a second end surface area oppositethe first end surface area, and the first end surface area is smallerthan the second end surface area.
 3. The electronic device according toclaim 2, wherein, the first end surface area is connected to theelectrode, and the second end surface area is connected to the throughthe via plug.
 4. The electronic device according to claim 1, wherein,the plurality of external electrodes have a first external electrode onthe second main surface overlapping the second semiconductor chips and asecond external electrode on the second main surface not overlapping thesecond semiconductor chip in the plan view.
 5. The electronic deviceaccording to claim 1, wherein, an insulation resin is formed on thesecond main surface of the interconnect layer, the insulation resin hasan opening in which external electrodes were formed, the opening has afirst end and a second end opposite the first end, and a diameter of thefirst end is smaller than a diameter of the second end.
 6. Theelectronic device according to claim 5, wherein, a second conductiveplug is formed in the opening and corresponds to a portion buried in apart of a solder ball.
 7. The electronic device according to claim 1,wherein, the first semiconductor chip, the second semiconductor chipsand the third semiconductor chip are mounted in a flip chipconfiguration on the interconnect layer.
 8. The electronic deviceaccording to claim 1, wherein, the first conductive plug is of a taperedshape which becomes smaller in a diameter as approaching to theinterconnect layer.
 9. The electronic device according to claim 6,wherein, the second conductive plug is of a tapered shape which becomessmaller in a diameter as approaching to the interconnect layer.
 10. Theelectronic device according to claim 1, wherein, a length of the secondsemiconductor chips is longer than a length of the third semiconductorchip along a length of the interconnect layer in the cross section view.